Booleans modifier glitching meshes
Change slightly Strenght value of first Displace modifier.
Or move vertices a bit on Y axis.
In this case t is caused by first Displace modifier that brings vertices in conflict position for boolean operation. Usually it is some overlapping geometry that creates weird cut that collaps all system :)
Sometimes helps to change Overlap Threshold value, but not in this case. In general just change a bit topology in any way.